An internal combustion engine typically has three chambers: the crankcase; the timing case; and the cylinder head cover. Each of these chambers must be openly connected to allow free flow of bypass gases and air movement during engine running.
In the engine, blow-by gas can escape past the piston into the crankcase where it mixes with airborne oil droplets. Rather than simply venting the blow-by gas to atmosphere, a closed breather system can be provided so that the blow-by gas is fed back into the engine induction system. This reduces the emission of unwanted gases.
It is desirable to include, in the breather system, means to retrieve oil contained in the blow-by gas and return this to the engine lubricating oil system for re-use. Otherwise the liquid oil, if allowed to enter the engine induction system (oil carry-over), can cause fouling of such components as turbocharger compressor vanes and engine poppet valves. Also, the liquid oil can form carbon deposits on the valves which can be detrimental to the performance of the intake air system. In addition, there will be a reduction in the volume of oil available for lubricating and cooling purposes.
A baffle may be provided in the cylinder head cover of the engine to impede oil carry-over. While this may lead to satisfactory performance in most applications, a particular problem exists for the engines of excavating work machines. Hydraulic excavators typically have an upper assembly that houses the engine, and a lower drive assembly. The upper assembly is rotatable relative to the lower assembly. Rotational acceleration or deceleration of the upper assembly leads to significant splashing of the oil within the engine which can increase oil carry-over.
It is known to provide a baffle having a perforated portion to limit oil carry-over. Such an apparatus is disclosed in EP 1,030,038. The apparatus includes a perforated triangular conduit fluidly connected to the breather gas inlet so as to allow the breather gas inlet to be located within the crankcase of the engine.
The present invention is directed to solving one or more of the problems set forth above.